1. Field of the Invention
The present invention relates particularly, though not exclusively, to a data communication device, a data communication system, and a data communication method in which storage areas of storage devices connected via networks to the data communication device and the data communication system can be accessed.
2. Description of the Related Art
Recently, the number of systems in which data processing devices such as personal computers (PCs) or multi functional printers are shared among a plurality of users has increased. The background to this may be that many recent data processing devices include high-capacity storage devices, and thus, even when the data processing devices are shared among a plurality of users, each user can store the user's own data in the data processing devices. Accordingly, a type of data processing device has come into use, which has a user authentication function to ensure security of data stored in the data processing device. In many cases, a user identification (ID) and a corresponding password are input, or an integrated circuit (IC) card on which user information is recorded is used for user authentication. Thus, log in and log out operations can be easily performed when the data processing device is used.
Recently, a type of system has come into use, to which a plurality of data processing devices are connected via a network. For example, a plurality of data processing devices are connected to a system via a local area network (LAN), such as a company LAN or a home LAN, or the Internet.
In these environments, a user may operate one data processing device to access data stored in another data processing device to which the one data processing device is connected via a network. For example, the user can submit an instruction to move data stored in one data processing device to a storage area of another data processing device. Moreover, a user can readily move data stored in one data processing device operated by the user or data input by scanning an original document using a scanner provided in the one data processing device to a storage area of another data processing device.
When access to storage areas of data processing devices on networks is facilitated in this way, a problem of security occurs. That is to say, when any user can access data stored in data processing devices on networks, confidentiality of data cannot be secured.
Thus, when data processing devices or storage areas to be accessed via networks are shared among a plurality of users, in addition to authentication of the users, who operate the data processing devices, access rights to the data processing devices or the storage areas need to be assigned to the individual users. Items of data that can be accessed by users can be restricted by determining data processing devices or storage areas that can be accessed via networks by individual users, authenticated by a user authentication function. In this arrangement, only authorized users can access the individual items of data via networks to update or move the items of data.
For example, a data communication system is disclosed in Japanese Patent Laid-Open No. 2001-188699, in which data is shared among a plurality of users via networks and access to the shared data is controlled for each user. Such a system is currently used in intranets, LANs, or the like.
However, a problem may occur when a user operates one data processing device to process data stored in a storage area of another data processing device to which the first data processing device is connected via a network. For example, the user first operates the one data processing device to log in the other data processing device to access the other data processing device and the storage area. In this situation, when the user logs out of the one data processing device while the data is being processed using the storage area, data processing is aborted at that point, as shown in FIG. 9A.
The term “log in” shown in FIG. 9A means that the user is put in a status in which the user can submit an instruction to perform processing using functions of the one data processing device. The term “log out” shown in FIG. 9A means that the user is put in a status in which the user cannot submit the instruction. The term “enable access” means that access to the storage area in a network is enabled. The term “disable access” means that access to the storage area is disabled.
Thus, in the known art, the user needs to keep logging into the one data processing device until processing of the data in the storage area of the other data processing device is completed, so that data processing is not aborted. Accordingly, the user, who operates the one data processing device, needs to wait for completion of data processing in the other data processing device to log out of the one data processing device. In this situation, the user needs to attend the one data processing device until data processing is completed. Thus, the operation is inefficient, because when the amount of data to be processed is large, a long period of time is necessary before the user can log out of the one data processing device after data processing is started.